Hi

At what age should speakers have their capacitors replaced? I've read that they eventually dry out and stop working properly, but there doesn't seem to be much on how to tell if they need replacing.

Cheers, Edd

Hi Edd,

 I don't think you can put a specific age to them. I have a pair of Beovox 1000's still sounding great on their original components, and a slightly younger pair of 1200's that needed capacitor replacement. As long as the top end still sounds good I'd go with the rule "if it aint broke dont fix it".

Cheers,

Steve
 

Of course you can never make a solid rule and there are exceptions, but it seems that the capacitors used by B&O during the 60's tend to last much longer than the never ones. It's safe to say that all 1970's and 80's equipment will need new capacitors by now if not already replaced. Speakers are too often overlooked and their caps are often leading a hard life, some even being slightly underdimensioned as I see it. Remember that capacitors used in speaker crossovers are generally non-polarized (bipolar) types since they work with AC signals.

Capacitors will decay over time, it doesn't happen overnight so most often noone notices any difference. At least up until the point where the caps are replaced, surely quite a few owners are in for a very nice surprise. Capacitor kits are readily available for the main part of the 70's and 80's B&O units.

Martin

Thanks for the advice

Thing is I'm not sure what my speakers are supposed to sound like as I've only had them a few months! They're RedLine 45.2s which would make them late 80s-early 90s, and I suspect the last owner kept them in his garage/shed. They're by far the best speakers I've ever owned, but if I had to criticise I'd say that the high end does sound slightly muffled. Maybe I should do one and see if I can notice a difference.

eddglynn:

Thanks for the advice

Thing is I'm not sure what my speakers are supposed to sound like as I've only had them a few months! They're RedLine 45.2s which would make them late 80s-early 90s, and I suspect the last owner kept them in his garage/shed. They're by far the best speakers I've ever owned, but if I had to criticise I'd say that the high end does sound slightly muffled. Maybe I should do one and see if I can notice a difference.

Definitely worth a go - cheap and simple enough to do (assuming you can operate a Screwdriver and a Soldering Iron). Hopefully the top end will improve, if not at least you know the crossover is good for another 10 or so years.

If you replace bipolar capacitors, then use Epcos/WIMA MKP or FKP polypropylene types. They sound much better than the electrolytic ones, much cleaner. The company Intertechnik also manufactures MKP ones, not quite so expensive, but really good.

The other advantage is, they will almost never decay ever again. :)

I would agree, if you can stand the size difference. If you can then the life will be orders of magnitude longer and the disapation factor orders of magnitude lower than an equivalent value electrolytic.

Usually the Wima oder Intertechnik polypropylene capacitors have almost the same size, it should fit on the board for the loudspeakers. At least up to around 10uF. Above 10 uF these plastic capacitors become really big... 68uf 100V is like a fat mono cell battery. But in a Penta is a lot of empty space ;)

 I have modified several redlines, especially the tweater becomes much better and cleaner if you replace the bipolar elko by an Wima MKP.

Martin

Hi there,

I own Beovox S80.2 loudspeakers.

My father bought them with a Beocenter 5500 20 years ago, so they are as old as I am :)

He recently gave them to me.

I noticed that the woofers needed some repair stuff (used rings), so I ordered a repair kit. But now I think about changing the capacitors, I think that now is the time to do it, in order to give my S80.2 a "new youth"!

Has anyone done this on S80.2 yet?

I need your help, for I don't know which kind of capacitors to use, and I don't know if I need to replace them all.

Thank you for answering !

Some of the original caps are (in my opinion) slightly underdimensioned from the factory. In speakers like this I would recommend mounting no less than 100V components., they are all axial bipolar if my memory serves me right.
A capacitor kit is readily available and I would recommend you replace the lot while in there.

Martin

I've just pulled apart my 4 S45's - I've been wanting to replace the Crossover caps for a while - Each Xover has 2x 16uF 100V Polarized Aluminium Electrolytic caps.

1. Being polarized (unusual - as Martin correctly stated that they have to deal with AC signals), I presume that it's OK to replace with Polarized - the Vishay Sprague Atom caps come to mind as suitable - available from Mouser at about $7.00 a shot. Any opinions on these?

http://www.mouser.com/search/refine.aspx?Ntt=75-TVA1803.1

2. Assuming we take the general rule, and replace with Bipolars (I couldn't find Wima's or Epcos' at 16uF), how about the Auricaps? Not cheap, but we get a 50% discount off retail - If anyone else wants - just PM me, and I'll be happy to include your order with mine.

http://www.audience-av.com/capacitors/a_prices.php

What would be the better choice here?

Regards

M Yachad

 

Are you really sure, that the crossover has polarized capacitors? Really really sure?  100% ?

 Usually they are all bipolar. If you use polarized capacitors and there should be bipolar, then you wont have fun with these parts. More or less they will get destroyed with all consequences...

 The auricaps should work, they are an equivalent for the Wima.

Hi Die Bogener,

Firstly, thanks for being sceptical - it keeps us honest!

Here is a picture - you can see very clearly that it IS a POLARIZED cap 16uF/40V .

The negative end has a clear ring, and the positive end has a clear + sign.

All 4 of my S45's have exactly the same capacitors. 

I haven't opened any other types of Beovox speakers - maybe someone else can figure out why this Type 6302 uses Polarized caps.

Regards

M Yachad

 

OK, you are right, these are really polarized caps, 100%.

A bipolar cap consists internally of two polarized caps with common ground.

Maybe this fact was used to design this crossover network. 2 polarized caps are cheaper than 1 bipolar.

The circuit plan would be very interesting ;) Sorry, i dont have this plan, to old...could somebody post it?

Would you still recommend Auricap BiPolars for replacements, or would it be better to remain with Sprague Atom Polarized?

Neither nor... first check the circuit plan. The best sound are (bipolar) polyethylen or polycarbonate plastic capacitors. But it is more important, not simply to replace parts, but to understand why B&O and the designer used this parts.

 Maybe it's pssible, to reduce parts or even to improve the design. 

Here' s the circuit

If the amplifier output stage has a single-ended power supply then polarised caps are OK, although I'm not sure how you can be certain that this will always be the case in a pair of passive speakers.

In this plan are bipolar caps used, no polarized.

So, somebody has replaced your caps with the wrong ones. They are definitely wrong.

In this application plastic capacitors (type WIMA MKP or MKT ) should make the best sound, dont use standard electrolytic bipolar caps.

Die_Bogener:

In this plan are bipolar caps used, no polarized.

So, somebody has replaced your caps with the wrong ones. They are definitely wrong.

In this application plastic capacitors (type WIMA MKP or MKT ) should make the best sound, dont use standard electrolytic bipolar caps.

Agreed - although bipolar caps will certainly be better that whats in-circuit at the moment! (and they are less likely to go CRACK! that the current parts).

Yes, quite normal bipolar electrolyt caps were probably used. And they would work fine... and they are very cheap. I think, 2-3 Euro in total.

But if you want to improve the sound, use plastic ones.

Electrolyt types have some acoustic problems, they cause audible distortions. 

Thanks - all of you!

Just for confirmation, 2 of the speakers were bought new, and have never been altered, and the other 2 (even though I bought them second hand) have the same capacitors, so the polarized capacitors are original ROE factory B&O installed.

Be that as it may, the plan very clearly specifies Bipolar, so therefore, that's what I'll use. 

Martin mentioned earlier that he thinks that the original spec caps are generally underdimensioned. 

Would it be prudent to remain with that exact 15uF circuit specification, or go to a 16uF or larger?

 

When Martin said they were under dimensioned I believe he was referring to the voltage rating. Changing the capacitance will alter the cutoff frequencies of the various filters in the cross over and is not a good idea. If you can get the same capacitance with a higher voltage rating (and temperature if possible) should mean the capacitors will be slightly more robust than the originals.

I'm amazed these parts were factory fitted and would be interested to hear from anyone how this was the case.

I'm also surprised that B&O fitted these caps in this loudspeaker... usually they should fail after some time.

 Use the same capacity, 15 or 16uF doesn't make a difference, but use 100V types. I would prefer 100V, it's more reliable. If a 40/63V cap fails, it can cause severe damage to a speaker...

Hello

It seems that you are speaking about capacitors , so this is the right place for a question that doesn't let me sleep...

I found AUDIO CAPACITORS (470uF 16V - 6,32 euro), so I'm wondering about their use in electronic circuits like amplifiers etc, it is right to change each capacitor with this AUDIO one or only in exact part of the electronic circuit like filter ?

How we can choose a capacitor (for example electrolyitic but not AUDIO) where there are tons of the same capacity and voltage but different prices? How is possible to choose the best one?

 

ciao ciao